soft-gusa
Software gUSA sequences (SH3* and SH4* only). On SH4A targets this
will now also partially utilize the movco.l and
movli.l instructions. This is the default when the target
is sh3*-*-linux* or sh4*-*-linux*.

-

hard-llcs
+

hard-llcs
Hardware movco.l / movli.l sequences
(SH4A only).

-

soft-tcb
+

soft-tcb
Software thread control block sequences.

-

soft-imask
+

soft-imask
Software interrupt flipping sequences (privileged mode only). This is
the default when the target is sh1*-*-linux* or
sh2*-*-linux*.

-

none
+

none
Generates function calls to the respective __atomic
built-in functions. This is the default for SH64 targets or when the
target is not sh*-*-linux*.